Comorbid cigarette smoking and heavy drinking (HD) - for women consuming 8+ drinks a week or 4+ drinks on a single occasion and for men consuming 15+ drinks a week or 5+ on a single occasion - is a major public health concern. Smokers engage in HD at high rates, and HD is robustly associated with low rates of smoking cessation. Furthermore, smoking and HD combine to dramatically increase the risk of head, neck, and pancreatic cancers in addition to having strong detrimental effects on overall health. To address this public health challenge, we have developed and tested a counseling approach that incorporates brief alcohol intervention into smoking cessation counseling. In both face-to-face and telephone formats, this combined counseling approach has demonstrated substantial promise for improving both drinking and smoking outcomes compared to matched control conditions? Adapting this approach for use in a web-based smoking cessation program for HD smokers is a compelling next step for increasing its population reach. Millions of smokers search online for smoking cessation information each year, and hundreds of thousands register on publicly available web-based cessation programs, yet none of these sites address heavy drinking in a comprehensive and integrated manner. A website specifically designed for HD smokers would provide an exceptional opportunity to enhance smoking cessation rates and concurrently intervene on HD. The overall objective of this project is to develop and pilot test a web-based smoking cessation program that specifically addresses HD. The project builds upon a well-established, evidence-based smoking cessation website, BecomeAnEX.org, which enrolls approximately 2,300 new users each month. The project will occur in two stages. In Stage 1a, we will to create EX-HD, an expanded mirror version of BecomeAnEx.org that incorporates key elements of our previously tested approaches for addressing HD in smoking cessation and NIAAA's evidence-based website for HD, Rethinking Drinking. We will pilot this beta version of EX-HD with 30 HD smokers recruited from BecomeAnEX, examining feasibility and acceptability using participant feedback and site use metrics. EX-HD will be revised in response to this feedback in preparation for Stage 1b work. Stage 1b will involve a pilot randomized clinical trial in which 120 HD smokers recruited through BecomeAnEX will be randomly assigned to either the standard BecomeAnEX program or to EX-HD and followed for 6 months in order to obtain initial estimates of the potential of EX-HD to reduce HD and increase smoking cessation. Results will provide the foundation for a fully-powered Stage II randomized trial. Ultimately, this research could result in a well- specified, efficacious intervention that wuld have great population reach with limited cost relative to in-person counseling and could have an especially powerful impact on public health by concurrently increasing smoking cessation and reducing HD.